Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'Meaning and Necessity' and 'Straw Dogs'

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19 ideas

1. Philosophy / D. Nature of Philosophy / 7. Despair over Philosophy
Human knowledge may not produce well-being; the examined life may not be worth living [Gray]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
The various logics are abstractions made from terms like 'if...then' in English [Hacking]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
13. Knowledge Criteria / C. External Justification / 9. Naturalised Epistemology
Knowledge does not need minds or nervous systems; it is found in all living things [Gray]
16. Persons / F. Free Will / 5. Against Free Will
The will hardly ever does anything; most of our life just happens to us [Gray]
19. Language / C. Assigning Meanings / 8. Possible Worlds Semantics
The intension of a sentence is the set of all possible worlds in which it is true [Carnap, by Kaplan]
25. Social Practice / A. Freedoms / 5. Freedom of lifestyle
Nowadays we identify the free life with the good life [Gray]
27. Natural Reality / G. Biology / 4. Ecology
Over forty percent of the Earth's living tissue is human [Gray]
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
Without Christianity we lose the idea that human history has a meaning [Gray]
What was our original sin, and how could Christ's suffering redeem it? [Gray]